1. Field of the Invention
The invention relates to a weighing machine, more particularly to a hydraulic weighing machine that is both durable and precise.
2. Description of the Related Art
A conventional weighing machine, e.g. a spring balance scale, is usually composed of a scale plate and a plurality of levers and springs that cooperate such that, when the user places a load on the weighing machine, the load will be transferred to the levers in order to move a pointer relative to the scale plate so as to indicate the weight of the load.
It is noted that the levers used in the conventional weighing machine are susceptible to wearing and the springs are susceptible to elastic fatigue such that the sensitivity of the weighing machine will decrease and the weighing machine will be unable to show the precise weight of the load after a period of use.
Therefore, the main object of the present invention is to provide a hydraulic weighing machine which is capable of overcoming the aforesaid drawbacks of the prior art.
Accordingly, the hydraulic weighing machine of this invention comprises a base, a weighing platform, an expandable bag, an upright stand, and a vertically extending weight scale. The base has a load bearing side. The weighing platform is disposed on the load bearing side of the base. The expandable bag is disposed on the load bearing side of the base, and supports the weighing platform thereon. The bag is filled with a liquid body. The upright stand is disposed adjacent to the base. The vertically extending weight scale includes a transparent tube that has a bottom end in fluid communication with the bag and a top end hung on the stand. The weight scale further includes a set of graduations to indicate a weight value corresponding to liquid level in the tube. When pressure is applied on top of the weighing platform, the bag will be pressed toward the load bearing side of the base, and the liquid body in the bag will be forced to flow into the tube so that the liquid level in the tube rises accordingly. Thus, an indication of the weight value corresponding to the amount of the applied pressure can be obtained from the graduations.